Screw driver



NOV' 25, 1930. J. A. ANDERsoN 15782581'- SCREW DRIVER Filed Dec. 24,1929 3 Patent ed `Nov. 2 5, 1930 CRA' , 1 UNITED; STATES' CORPORATION OFCONNECTICUT PATENT*OFFICE? JOHN A. AixTsDERsoiv,` or BRIDG-Eron'r,oonnncriounnssieivon roman imrnenronr i HARDWARE MANUFAGTURINGCORPORATION,zorrnrnenrom, oonnnofrmnr; 'A i sonnw DRivER p y I Thisinvention relates to sorew drivers,

and has for an object to improve upon the vide a construction which canbe used to effectively operate screws in which the kerf has been sodeformed as to be incapable of operation by the ordinary plain screwdriver.

With the foregoingand other objects in' view, the invention consists incertain novel features of constructlon and arrangement of parts as willbemore fully disclosedin `coni sharp to bite into the side walls ofrthekerf 17 of the screwV head 18 upon turning4 '14. 11 and 12 there isprovided a transverse rib nection With the accompanying drawing.

In this Vdrawing` Ihg. 1 is a side .elevatlon ofa screw driver shankconstructed according to the preferred embodiment'of the invention;

Fig. 2 is a fragmentary 'edge elevation of` the same on an enlargedscale showing the screw driver in the kerf of a screw.

Fig. 3 Vis an enlarged section substantially on line 34-8of Fig.'1.

Fignlis an enlarged end view taken substantially as indicated by' line4-4 ofFig. 1`,and

Fig. 5 is an enlarged fragm'entary longitudinal section 'substantiallyon line 5-5 of Fig-1.`

The shank of the screw driver, as is usual,'is provided vwith twoopposite side faces 11 'and 12 and two edge 'faces 13 and On either oneor both of the side faces '15 which extends transversely of Vthe bit'closely adjacent the free end 16 of the bit.

The free edge of this rib is sufliciently movement of the screw driverin the `kerf, and the biting action very effectively resists slipping ofthe bit from the kerf in a direct tion longitudinally of the shank. Theside wall of the kerf during the turning movement oftheibit to 3`prevent slipping of` the blt transversely in the kerf or to rresistjboth but Ihave shown in theaccompanyingdrawmg two series of'inclined`ribs 19` and .20, these `ribs being preferably arrangedlto extend`obliquely` from the longitudinal center line 21 to theop'poste" edgefaces 13 ``and 14 and inclined toward the free end 16.-` The,transversefand longitudinal slipping. Vari lous means may be providedfor doing this,V

angle of 'inclination may vary depending'onv whether it is desired toemphasize resistance to lateral slipping in the kerf or resistance toVlontgiltudinal i slipping. s Withthe ribs infrom the kerf and thus.`more eflectively assists in holding :it thekerfQThis construction`` andarrangement`` :using the transverse rib `E incombination with theotherholding means 11squlte an improvement over la conw struction inxwhichtheribs'19rand only areprovided andv run'o'utzthe endjlG. Particularlyisthis truein a casewhere the bit` is used in a kerf which is relatively,shallow orzhasrbeenbadlyiworn or deformed. In

such icases, the transverse' frib 151 materially' assists in gripping*.the kerf for operating .a

screw.- `Alsothe ribs-l`` strengthenthe freef end ofth'e bit whichis thethinnest poltion w of' the bit and 1 is` also.` the`l portion` which' isI `more'apttolbeibrokenoriinjilred. Theribs I 15` makel this endportionmuch stronger. r

The ribs .and holdingmeans may be fo'rmed a ;in anyimanner` desired asfor example, raising r them 4on the surface or by providing grooves ordepressions in the surface.` It is alsonot necessary -thatthe edges ofthe ribs be particularly sharp as all that is necessary is that they besufiiciently sharp to bite into the side walls of the lrerf sufficientlyto holdthe bit against slipping.` It is also not necessary that the.auxiliary holding means above the transversewribsl be as shown on thedrawing as other shapes and arrangements ofsharp edged means may beprovided to bite into the side walls of the kerf in the turningoperation. i

In use the bit is inserted in the kerf in the same way as is any screwdriver, and this screw driver does not require a special form of screwor kerf, but can be used with any standard or other screw having a kerf.As a matter of fact, it will grip into a kerf which has been greatlyworn or deformed to such an extent as to be practically impossible ofuse for operation of the screw by the ordinary m plain screw driver. Thetransverse rib 15 is particularly useful in certain kinds of kerf as itvery effectively bites into the side walls thereof closely adjacent thevery bottom of the kerf. rl`he width of the kerf is practically 15innnaterial as this device is effective in both relatively wide andnari'ow kerfs.

Having thus set forth the nature of my invention, what I claim is:

1. A screw driver comprising a shank pro- 2,9 vided with a screw drivingbit having two opposite side faces, one of said faces being providedwith a rib extending transversely of said face closely adjacent the freeend of the bit and extending laterally outward, said face also havingribs extending from a central longitudinal line of the shank at anoblique angle to the shank toward said first rib, said obliquerribs andthe transverse rib blending into each other so that they form Socontinuations of each other and are adapted to engage a wall of a screwhead kerf to resist both longitudinal and transverse slipping of the bitin the kerf during the turning moveinent of the screw driver.

25 2. A screw driver comprising a shank provided with a screw drivingbitihaving two opposite side faces and two edge faces joining the sidefaces, each of the side faces having a rib extending transversely ofsaid face ,io closely adjacent the free end of the bit, each of the sidefaces also having ribs extending from a central longitudinalline of theshank and at an oblique angle to the shank toward said edge faces, theoblique ribs nearer the :+1 end of the bit and the transverse ribsblending into each other to form continuous ribs adapted to engageopposite walls of a screw head kerf to resist both longitudinal andtransverse slipping of the bit in the kerf dur- 511 ing the turningmovement of the screw driver.

In testimony whereof I affix my signature.

JOHN A. AND'ERsoN.

